1. Field of the Invention
This invention relates to a muscle exerciser, and more particularly to a thigh exerciser.
2. Description of the Related Art
Referring to FIG. 1, a conventional thigh exerciser 100 includes a pair of vertically extending slide rails 101 assembled within a generally vertical frame 1, and a stack of weights 102 through which the slide rails 101 are inserted. The vertical frame 1 has top and bottom support bars 2, 3 extending forwardly and respectively from central top and bottom ends thereof. The bottom support bar 3 has a front end connected with a seat frame 4. The top support bar 2 has a front end connected with a front support bar 5 which extends downwardly and inclinedly therefrom and which has a bottom end connected to the seat frame 4. A backrest member 501 and a seat member 401 are respectively connected to a middle section of the front support bar 5 and a top portion of the seat frame 4. The seat member 4 is provided with a pair of support tubes 402 below the seat member 401. The support tubes 402 of the seat member 4 are connected respectively with rotary discs 404 at top ends thereof, and are sleeved respectively onto axial rods 403. Cooperation between the support tubes 402 and the axial rods 403 may be used to vary the opening angle of the thigh exerciser 100 in a known manner. The rotary discs 404 are fixed respectively with support rods 405, each projecting outwardly from a top face of the respective rotary disc 404. The support rod 405 of each rotary disc 404 is connected with a knee support 406 and an upright pad 407. The axial rods 403 are fixed respectively with sector-shaped cams 408 at bottom ends thereof. The sector-shaped cams 408 are connected respectively with two belts 6 that wrap respectively around the sector-shaped cams 408. The belt 6 is connected to a pulley unit 103, which is connected pivotally to the bottom support bar 3, another pulley unit 301 mounted on the top end of the vertical frame 1, and the stack of weights 102.
To use the conventional thigh exerciser 100, a user sits on the seat member 401 with his/her back on the backrest 501 and his/her legs straddled over the respective knee supports 406. The thighs of the user then press the upright pads 407 toward each other, urging the support rods 405, the rotary discs 404, the support tubes 402, the axial rods 403, and the sector-shaped cams 408 to rotate synchronously, thereby permitting the belt 6 to lift the stack of weights 102. The combined force applied by the user's thighs at this time must be sufficient to lift the stack of weights 102 so as to achieve training of the user's thigh muscles.
Although the conventional thigh exerciser 100 can achieve its intended purpose, the structure of the conventional thigh exerciser 100 is complicated and bulky. Furthermore, in the case where the user has selected to exercise with a large number of the weights from the stack of weights 102, when the applied force of the user's thighs is released so as to proceed with the next pressing movement (i.e., during the negative portion of a repetition), the stack of the weights 102 is prone to quickly fall. If this occurs, the upright pads 407 are abruptly moved toward their original positions, which may result in injure to the user's thighs. Moreover, when the user desires to adjust the load to enhance training of the thigh muscles, he/she has to move to the back of the thigh exerciser 100 and manipulate the stack of weights 102 in a know manner. This is a troublesome process.